The present invention generally relates to an improved conveying system, which may be employed for moving packages through a station at which a package is weighed followed by a station at which a label bearing package weight/price indicia is applied to the weighed package.
A problem inherent in weighing-labeling machines is the necessity of first moving a package to be weighed from the conveyor to a weigher and then returning such package to the conveyor without interrupting conveyor movement or adversely influencing operation of the weigher or increasing the period of time required by the weigher to perform a weighing operation. Opposite approaches to this problem are disclosed for instance by U.S. Pat. Nos. 2,597,069 and 3,394,792.
In U.S. Pat. No. 2,597,069 transfer of packages from a conveyor to a weigher and from the weigher to the conveyor is achieved by projecting elements of the weigher upwardly between transversely spaced elements of a continuous belt type conveyor whereby to lift the package from the conveyor; the weigher elements being subsequently retracted at the completion of the weighing operation in order to re-position the weighed package on the conveyor for discharge from the weighing station. A serious drawback of this type of machine is that the required vertical displacement of the weigher produces substantial vibrations, which must of course be dampened before the weighing operation can proceed. As a result only a relatively low speed weighing and labeling operation can be achieved with this type of machine.
An increase in speed of the weighing operation may be theoretically achieved by employing a machine of the type disclosed in U.S. Pat. No. 3,394,792, which features an arrangement wherein a portion of a conveyor passing through a weighing station is lowered and raised relative to a weighing platform such that vertical deflections or movement of the platform are essentially limited to those induced by the weight of the package. However, the operational speed of this type of machine is limited by the requirement that the conveyor cannot be driven at a speed above that at which an article when placed upon the weighing platform will slide off such platform or be incorrectly positioned thereon. Moreover, as the speed of the conveyor and thus the package is increased, the tendency of the weighing platform to be subjected to tilting vibrations increases. Since these vibrations must also be dampened to avoid inaccuracies in the weighing operation, a definite limit is placed on permissible speed of the conveyor.